N-Nitrosobis(2-oxopropyl)amine (BOP), a further postulated beta-metabolite of di-n-propylnitrosamine, induced a high incidence of pancreatic duct adenomas and adenocarcinomas as early as 13 weeks in Syrian hamsters receiving weekly sc injections for life and a few pancreatic adenomas, after 28 weeks, in those given a single sc dose. Compared to related compounds, N-nitrosobis(2-hydroxypropyl)amine and N-nitrosobis(2-acetoxy-propyl)amine which are also pancreatic carcinogens, BOP induced only a few neoplasms of the lung, liver, and kidney and none in the nasal cavity, larynx, and trachea. The results therefore indicate progress in developing a more specific model for pancreatic carcinogenesis studies.

The epiphyseal growth plate of the domestic pig was investigated topologically combining biochemical methods with electron microprobe microanalyses both correlated to histological controls. A lateral resolution of about 50 micrometer was reached. Highest nuclease activity was found in the lower columnar cell zone, while alkaline phosphatase showed maximal activity in the hypertrophic area, connected with maximal values for extractable, organically bound phosphorus, and extractable Ca and Mg. Acid phosphatase activity reached maximal values in the zone of the lower primary spongiosa, while the extractable Pi had maximal values at the end of the zone of bone remodelling. Microprobe analyses have shown that the extracellular Ca content (per dry mass) remained relatively constant at 0.7% (about 58 mM/kg wet weight for 66% tissue fluid) in all zones of the plate increasing to 1% in the vicinity of the first foci of mineralization. The intracellular P content (per dry mass) was about 4.5 %, the extracellular 0.1-0.2% (about 10-20 mM/kg wet weight) increasing also to about 1% in the vicinity of the first foci of mineralization. Thus the Ca X P product was much higher than the ion-product of 2 mM2 which is necessary for an in vitro mineralization of connective tissue. The extracellular S content (per dry mass) as a probable indicator of sulfated proteoglycans was relatively constant at about 3.5% in the different zones but decreased to about 0.3% in the fully mineralized regions. This indicates a loss of sulfur containing substances with mineralization which is not so high since the concentrations per dry mass must be normalized to a unit volume of equal density of mass.

Hamsters of three types designated as inbred cream (Epp/e/e), linebred white (EPP/cdcd/RB/A), and linebred albino (EPP/cdcde/e) were thoroughly examined histopathologically for spontaneous diseases. All hamsters were maintained simultaneously for life under identical standard laboratory conditions. Marked differences were found in longevity of the animals and in incidence, sites, patterns, and types of spontaneous diseases. In cream hamsters (CH), survival time was shorter than in white hamsters (WH) and albino hamsters (AH). More tumors and malignant lesions unrelated to survival were found in AH compared to CH and WH; also, the multiplicity of neoplasms were more pronounced in AH. The predominating tumor types differed in each line: Pancreatic islet cell neoplasms were most common in CH, adrenal gland tumors predominated in WH, and thyroid gland tumors in AH. Also, the relative incidence of spontaneous tumors varied among the lines. Some tumors seemed strain-specific and were not seen in other lines; malignant melanomas, for example, occurred only in CH and WH. Certain neoplasms, e.g., those of the thyroid and adrenal glands, were found more often in one sex than the other. The three hamster groups differed also in nonneoplastic diseases. Detailed histopathologic findings are presented and compared with data on the Syrian golden hamster, the ancestral line of these three groups.

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The frequency of spontaneously occuring neoplasms in the urogenital system and endocrine organs was examined in two Syrian hamster colonies [Eppley colony (EC); Hannover colony (HC)]. With the exception of a renal adenoma in an EC female, the urinary systems of animals in both colonies were free of neoplastic growths. A single epididymal adenoma of the male fenital system (EC) was found. However, incidences of female genital tract tumors were 10 (EC) and 3.5% (HC) and accounted for 34 and 11%, respectively, of all tumors in females. Among all genital tract tumors, 3 (EC) and 57% (HC) were ovarian, 14% (HC) were in the fallopian tubes, 81 (EC) AND 29% (HC) were uterine, and 16% (EC), vaginal. The overall incidence of endocrine organ tumors was similar in both colonies (EC, 22%; HC, 19%). The distribution of these tumors was as follows: pituitary gland; EC, 3%, HC, 0; thyroid gland: EC, 28%, HC, 31%; parathyroid gland: EC,11%, HC, 18%; adrenal cortex: EC, 42%, HC, 31%; adrenal medulla: EC, 7%, HC, 0; and endocrine pancreas: EC, 10%, HC, 31%. The morphology of these neoplasms is described and the incidence compared with those reported in other colonies.